Closure for exhaust stack



United States Patent Earle S. Snader Ellicott City, Maryland 776,397 Nov. 18, 1968 Dec. 8, 1970 KoppersCompany, Inc.

a corporation of Delaware lnventor Appl. No. Filed Patented Assignee CLOSURE FOR EXHAUST STACK 2 Claims, 4 Drawing Figs.

US. Cl. 98/59, 49/386: 220/36 Int. Cl. F23l 17/10 Field of Search 98/59, 122;

[56] References Cited UNITED STATES PATENTS 1,289,074 l2/l9l8 Armagost 49/357X 2,408,132 9/1946 Weeks.... 220/36UX 2,771,834 11/1956 Goudy.... 98/59 2,832,585 4/1958 Hansen 266/31 Primary Examiner-William E. Wayner Attorneys-Sherman l-l. Barber, Boyce C. Dent and Olin E.

Williams ABSTRACT: A closure for an exhaust stack includes a hinged member that is counterweighted and is pivoted by cables connected to screwjacks. The screwjacks are motor-driven or they may be manually driven in case of a power failure.

PATENTED DEE 8197B SHEET 2 BF 2 INVENTOR EAPLE s. SNADER 1 CLOSURE FOR EXHAUST STACK BACKGROUND, OF Tl-IE INVENTION Air pollution has become so serious of late that morestringent smoke and exhaust control codes make it necessary to remove from exhaust gases all, or most all, of the polutants before the exhaust gases are discharged to atmosphere. One method to remove the solid materials from the exhaust gases is by passing the gases through a precipitator of the electrostatic type, which removes and collects most of the particles of dirt and solid matter from the exhaust gases.

Ordinarily, exhaust stacks are open to the atmosphere and gases pass through them upwardly without restriction. To effectively divert these exhaust gases into a gas-scrubbing device, such as an electrostatic precipitator, one would suppose that some sort of damper or internal valve could be used. But, butter-fly type valves, goggle valves, sliding plates, and the like, are not effective and are not acceptable under the stringent air pollution codes. The reason these types of valves are not acceptable is because of the possibility that dirt and encrustation matter in the gases, when combined with moisture such as rain or snow, can build up on the valve and prevent it from being operable in an emergency situation. Hence, there is needfor a closure or cover for an exhaust stack that provides an effective seal against the passage of gases to the atmosphere. Both closure or cover should be readily and quickly openable in emergency situations, such as when the gas-scrubbing device like the electrostatic precipitator becomes inoperative. I

How the equipment of the present invention fulfills this need is set forth in the following description of one embodimerit of the invention.

SUMMARY OFTHE INVENTION BRIEF DESCRIPTION OF THE DRAWING One embodiment of the invention is illustrated in the drawings wherein:

FIG. 1 is a schematic elevational view of a cover in accordance with the invention; FIG. 2 is a view along line Hell of FIG. 1;

FIG. 3 is a view along line III-Ill of FIG. 1; and

FIG. 4 is a detailed elevational view of aportion of the apparatus of FIG. antipollution DETAILED DESCRIPTION Referring to FIG. '1, apparatus 11 in accordance with the invention includes a closure or cover assembly 13 and a power assembly 15 to actuate the closure-or cover.

The cover assembly 13 comprises a circular plate 17 having a depending peripheral flange 19. The cover is, or may be readily fashioned from a conventional flanged-only head available commercially. The cover 17 is generally flat and is stiffened by a plurality of structural members 21, equally spaced apart and extending outwardly from the cover 17. The structural members 21 may be angle, l-beams, tees, or the channels suggested in FIG. 2. A counterweight 23 isattached to the extremities of the three outwardly extending stiffeners 21. The counterweight also may have any convenient form, such as an I-beam as suggested in FIG. 1, though otherforms may be used if preferred.

The stiffeners 21 are secured to ashaft 25 that is joumaled in bearings 27 mounted to structure that will be presently described. One outwardlyextending end of the shaft 25 is secured to a centrally pivoted balance arm 29.

The bearings 27 are mounted to a band 31 that encircles and is secured, as by welding, to the top of a stack 33. The band 31 is provided with a pair of spaced-apart bearing mounts 35, located about where shown in FIG. 1.

The band 31 has a topangular flange or ring 37 that supports a channel 39 in which thereis a suitable sealant material 41. The band 31 may also'be provided with a bottom flange if desired to provide additional local stiffening to the stack 33. When the cover 17 is in the closed position, as shown in FIG. 1, the flange 19 is embedded in the sealant material 41 to prevent the escape of dirty gases from the stack.

The power assembly 15 is located near the base of the stack 33 and is comprised of a segmented ring 43, having top and bottom flanges 45, that encircles and is welded to the outer periphery of the stack 33, and a platform 47 that is mounted to the encircling ring 43.

On the platform 47, which is angularly positioned about as shown in FIG. 3, there are mounted a reversible electric motor 49 and a pair of screwjacks 51, 53. The screwjacks 51, 53 are located below the ends of the balance arm 29 and are connected together in a manner described hereinafter.

Screwjacks 51 and screwjack 53 are coupled together as at 54, and both are driven simultaneously by the electric motor 49. The screwjack 51 is a right-hand screw and the screw jack 53 is a left-hand screw. Thus when the reversible motor 49 rotates in one direction, the screwjack 51 moves upwardly and the screwjack 53 moves downwardly.

The screw portion 51a of the screwjack 51 is connected to a calibrated spring 55 and the screw portion 53a of screwjack 53 is connected likewise to a calibrated spring 57. Each spring 55, 57 is connected to one end of a cable 59, 61 through a turnbuckle 63 that allows for adjustment in the tension in the cable 59, 63. The springs 55, 57 are of the calibrating type so that cable tension will not become excessive as the stack 33 expands when it is hot, and as the stack contracts when it is cold. The calibrated springs 55, 57 may be inserted in the cable runs 59, 61 instead of being attached to the screwjacks 51, 53 if desired; additional spring hangers may likewise be used if needed.

The cables 59, 61 are connected respectively to the left and right ends (as viewed in FIG. l)v of the balance arm 29, using a suitable type of connecter 67, such as a clevis and pin.

The worm shaft portion 65 of the screwjack 53 projects outwardly from the screwjack housing and is adapted to receive a flywheel-type manual crank"( not shown), which is operable to open or close the stack cover, or to move the cover to any desired intermediary angular position.

The respective screw portions 51a and 530 are each provided with an arm 67 which extends outwardly to engage a limit switch 69 just before the screw portion reaches its lowest position. The limit switches 69 interrupt the current to the motor 49 to prevent overrunning of the screwjack device wherefore it could be severely damaged.

Normally, a cover in accordance with the invention is closed when attached to an existing exhaust stack associated with gas-cleaning apparatus. But, should it be desired to open the cover for some reason, the motor may be actuated to turn the screwjacks. Since both screwjacks operate together, but in opposite directions, there is always positive control of the cover at all times during opening and also during closing of the stack. Since the, cover is counterweighted, it should be evident to those skilled in the art that only a small torque need be applied to the shaft to rotate the cover.

Those skilled in the art will recognize several important features and advantages of the present invention, among which are:

The screwjack mechanisms for opening and closing the cover are self-locking which assures accurate positioning of the cover in any desired position;

The calibrated spring hangers maintain substantially equal tension in the operating cables even though the stack has expanded due to heat, or has contracted due to being cold. In order to maintain such equal tension, the screwjack mechanisms are mounted to the stack and not to an adjacent supporting structure;

The exhaust stack cover makes a positive seal with the sealant in the channel portion of the upper band, so that no gases escape when the cover is in the close position;

The exhaust cover, being counterweighted, will open even though the open cable, or the open screwjack," should fail; it being only necessary' to relax tension in the closed cable to effect opening of the cover; and

The cover can be readily and quickly installed on an existing exhaust stack to effectively provide antipolution control in association with an effective gas-cleaning apparatus duly installed at a facility.

I claim:

1. Apparatus for closing an exhaust stack comprising:

a. a cover having a size and shape substantially equal to that of the stack at the top thereof;

b. a band encircling and connected top of said stack;

0. bearings mounted to said band;

d. a shaft journaled in said bearings, said shaft being connected to said closure e. a counterweight fixed to said cover;

f. a pair of screwjacks, one being a left-hand screwjack and the other being a right-hand screwjack;

g. cable means connecting each screwjack and said cover;

h. a coupling connecting together said screwjacks; and

i. a motor driving one screwjack whereby each screwjack moves its respective cable for positively moving said cap in either an opening or a closing direction.

2. The invention of claim 1 wherein:

a. said cable means includes a calibrated spring and a turnbuckle connected to each screwjack and connected to b. an arm mounted to said shaft to turn the shaft and pivot said cover. 

